Military police Captain Ricardo Pinto said yesterday that inmates of the penitentiary in the city of Cascavel took at least two warders and several other inmates hostage in the uprising.
He said that negotiations for better conditions in the prison were still under way 12 hours later.
Prisoners set some objects on fire and were using metal poles to cause damage to the 928-bed prison that houses more than 1,000 inmates.
Authorities initially said two men had been decapitated but later learned of a third prisoner who had been killed by being thrown off the building’s roof.
The revolt began before sunrise when a prison guard was captured during breakfast, Mr Pinto said.
Dozens of prisoners had climbed onto the rooftops, with their faces covered with white fabric, shouting while they beat men held with ropes around their necks, or whose hands were tied behind them.
The rioting inmates waved banners emblazoned with the initials PCC for a criminal prison gang formed in the 1990s.
Jairo Ferreira, a lawyer for the prison guards’ union, said that at one point the inmates put the decapitated head of a victim on the lap of a custodian who was initially held hostage and later freed.
Mr Ferreira said the prisoners had rioted to demand better food and medical care in the prison.
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